Instrument Cluster Description and Operation: Speedometer

The engine control module (ECM) sends the vehicle speed to the instrument panel module (IPM) via the serial data circuit. The instrument panel cluster (IPC) displays the vehicle speed as determined by the IPM. The IPC receives a serial data message from the IPM indicating the vehicle speed. The speedometer will default to zero if:

• The ECM detects a malfunction in the vehicle speed sensor circuit.
• The IPC detects a loss of serial data communications with the IPM.
• The IPM detects a loss of serial data communications with the ECM.